Experimental Investigation of Interstitial Fluid Effects on Particle Fluctuating Motion

2005 ◽  
Author(s):  
K. Hadinoto ◽  
J. Sinclair Curtis
Keyword(s):  
Interstitial Fluid ◽  
Stokes Number ◽  
Coefficient Of Restitution ◽  
Glass Beads ◽  
Viscous Force ◽  
Fluid Viscosity ◽  
Particle Collisions ◽  
Turbulence Modulation ◽  
Mass Flowrate ◽  
The Impact

The importance of interstitial fluid effects on particle fluctuating motion in gas-particle or liquid-particle flows with significant particle-particle collisions can be characterized by the ratio of the coefficient of restitution for inelastic particle-particle collisions in a fluid ef to the coefficient of restitution for collisions in a vacuum es. In previous research, the ratio ef/es has been found to depend on the impact Stokes number St, which relates the particle inertia to the viscous force. The value of the impact Stokes number is known to be a function of the particle velocity at impact, the size and density of the particle, and the fluid viscosity. In the present work, the effect of the interstitial fluid on particle fluctuating motion is investigated experimentally using LDV/PDPA in a vertical pipe flow configuration. The influence of the variation in the particle loading and Reynolds number, which affects the particle impact velocity and, hence, ef, is probed using particles of two different densities with comparable sizes. Specifically, the downward flow of 70 micron glass beads (density = 2500 kg/m3) and 60 micron hollow ceramic microspheres (density = 700 kg/m3) is investigated for solids loadings (ratio of solids mass flowrate to gas mass flowrate) from 0.4 to 7 and Reynolds numbers which vary from 6000 to 13,000. For this range of conditions, the values for ef range between 0.65 and 0.94 (0.94 is the value for es for glass beads colliding in a vacuum). Trends in the mean and fluctuating velocities for both the gas and particle phases, as well as the gas turbulence modulation in the presence of particles, are discussed in relation to the degree of influence of the interstitial fluid on the details of the particle motion.

scholarly journals Particle–wall collisions in a viscous fluid

2001 ◽  
Vol 433 ◽  
pp. 329-346 ◽  
Author(s):  
G. G. JOSEPH ◽  
R. ZENIT ◽  
M. L. HUNT ◽  
A. M. ROSENWINKEL
Keyword(s):  
Reynolds Number ◽  
Viscous Fluid ◽  
High Speed ◽  
Particle Density ◽  
Particle Surface ◽  
Density Ratio ◽  
Experimental Studies ◽  
Stokes Number ◽  
Coefficient Of Restitution ◽  
The Impact

This paper presents experimental measurements of the approach and rebound of a particle colliding with a wall in a viscous fluid. The particle's trajectory was controlled by setting the initial inclination angle of a pendulum immersed in a fluid. The resulting collisions were monitored using a high-speed video camera. The diameters of the particles ranged from 3 to 12 mm, and the ratio of the particle density to fluid density varied from 1.2 to 7.8. The experiments were performed using a thick glass or Lucite wall with different mixtures of glycerol and water. With these parameters, the Reynolds number defined using the velocity just prior to impact ranged from 10 to approximately 3000. A coefficient of restitution was defined from the ratio of the velocity just prior to and after impact.The experiments clearly demonstrate that the rebound velocity depends on the impact Stokes number (defined from the Reynolds number and the density ratio) and weakly on the elastic properties of the material. Below a Stokes number of approximately 10, no rebound of the particle occurred. For impact Stokes number above 500 the coefficient of restitution appears to asymptote to the values for dry collisions. The coefficients of restitution were also compared with previous experimental studies. In addition, the approach of the particle to the wall indicated that the particle slowed prior to impacting the surface. The distance at which the particle's trajectory varied due to the presence of the wall was dependent on the impact Stokes number. The particle surface roughness was found to affect the repeatability of some measurements, especially for low impact velocities.

Numerical investigation of particle–particle and particle–wall collisions in a viscous fluid

2008 ◽  
Vol 596 ◽  
pp. 437-466 ◽  
Author(s):  
A. M. ARDEKANI ◽  
R. H. RANGEL
Keyword(s):  
Viscous Fluid ◽  
Vortex Dynamics ◽  
Experimental Studies ◽  
Stokes Number ◽  
Coefficient Of Restitution ◽  
Computational Method ◽  
Particle Collisions ◽  
Fluid System ◽  
Collision Model ◽  
Good Agreement

The dynamics of particle–particle collisions and the bouncing motion of a particle colliding with a wall in a viscous fluid is numerically investigated. The dependence of the effective coefficient of restitution on the Stokes number and surface roughness is analysed. A distributed Lagrange multiplier-based computational method in a solid–fluid system is developed and an efficient method for predicting the collision between particles is presented. A comparison between this method and previous collision strategies shows that the present approach has some significant advantages over them. Comparison of the present methodology with experimental studies for the bouncing motion of a spherical particle onto a wall shows very good agreement and validates the collision model. Finally, the effect of the coefficient of restitution for a dry collision on the vortex dynamics associated with this problem is discussed.

Effects of Surface Roughness on Rebound Strength in Particle-Wall Collisions in Air and Liquids

2005 ◽  
Author(s):  
Y. Q. Nguyen ◽  
John C. Wells
Keyword(s):  
Surface Roughness ◽  
Qualitative Agreement ◽  
Rough Surfaces ◽  
Tap Water ◽  
Stokes Number ◽  
Glass Beads ◽  
Smooth Surfaces ◽  
Sugar Water ◽  
Glass Plates ◽  
The Impact

Experiments to examine the effects of surface roughness on the strength of rebounds from particle-wall collisions, in liquids and in air, are presented. The target walls are glass plates and have three different values of surface roughness: less than 0.3 μm, 10.5 μm, and 40.1 μm. Particles are glass beads with diameters from 1.05mm to 2.35mm. The experiments are conducted in tap water, sugar-water, and in air. Pre-impact Stokes numbers in liquids are in the range 20–170. For impacts in air, no significant effect of the surface roughness on rebound velocity is observed. In liquids, rough surfaces yield stronger rebounds than smooth surfaces. For a given ratio of surface roughness/particle’s radius, the enhancement of the surface roughness on the rebound compared to the smooth one increases when the impact Stokes number decreases toward the “rebound threshold”. These observations are in qualitative agreement with suggestions in the literature.

scholarly journals Stokes' cradle: normal three-body collisions between wetted particles

2010 ◽  
Vol 650 ◽  
pp. 479-504 ◽  
Author(s):  
C. M. DONAHUE ◽  
C. M. HRENYA ◽  
R. H. DAVIS ◽  
K. J. NAKAGAWA ◽  
A. P. ZELINSKAYA ◽  
...  
Keyword(s):  
Stokes Number ◽  
Solid Particles ◽  
Particle Collisions ◽  
Particle Deformation ◽  
Additional Resistance ◽  
Newton’S Cradle ◽  
Target Particle ◽  
Three Body ◽  
Regime Map ◽  
The Impact

In this work, a combination of experiments and theory is used to investigate three-body normal collisions between solid particles with a liquid coating (i.e. ‘wetted’ particles). Experiments are carried out using a Stokes' cradle, an apparatus inspired by the Newton's cradle desktop toy except with wetted particles. Unlike previous work on two-body systems, which may either agglomerate or rebound upon collision, four outcomes are possible in three-body systems: fully agglomerated, Newton's cradle (striker and target particle it strikes agglomerate), reverse Newton's cradle (targets agglomerate while striker separates) and fully separated. Post-collisional velocities are measured over a range of parameters. For all experiments, as the impact velocity increases, the progression of outcomes observed is fully agglomerated, reverse Newton's cradle and fully separated. Notably, as the viscosity of the oil increases, experiments reveal a decrease in the critical Stokes number (the Stokes number that demarcates a transition from agglomeration to separation) for both sets of adjacent particles. A scaling theory is developed based on lubrication forces and particle deformation and elasticity. Unlike previous work for two-particle systems, two pieces of physics are found to be critical in the prediction of a regime map that is consistent with experiments: (i) an additional resistance upon rebound of the target particles due to the pre-existing liquid bridge between them (which has no counterpart in two-particle collisions), and (ii) the addition of a rebound criterion due to glass transition of the liquid layer at high pressure between colliding particles.

Surface deformation and rebound for normal single-particle collisions in a surrounding fluid

2019 ◽  
Vol 871 ◽  
pp. 1044-1066 ◽  
Author(s):  
Angel Ruiz-Angulo ◽  
Shahrzad Roshankhah ◽  
Melany L. Hunt
Keyword(s):  
Time Scale ◽  
Surface Deformation ◽  
Stokes Number ◽  
Particle Collisions ◽  
Elastic Plastic ◽  
Viscous Losses ◽  
Wide Range ◽  
The Impact ◽  
Surrounding Fluid ◽  
Fluid Characteristics

This article presents experimental measurements involving immersed collisions between a rigid impactor and a deformable target for a wide range of Reynolds and Stokes numbers. Three aluminium alloys are used as solid targets submerged in seven different fluids covering a wide range of viscosity and density. The collision and rebound velocities as well as the depth and diameter of the crater produced by the collisions are measured with high resolution. Most of the experiments in this study occur at velocities for which the deformation is within the elastic–plastic regime. Results of the experiments in air are analysed by elastic, plastic and elastic–plastic theories, and demonstrate the complexities of modelling elastic–plastic collisions. For collisions in a liquid, the measurements show that the size of the crater is independent of the fluid characteristics if the Stokes number is beyond a critical value. The normal coefficient of restitution can be estimated by including both viscous losses and plasticity effects and assuming that the collision time scale is significantly shorter than the hydrodynamic time scale. The results of the crater dimensions are also used to develop an analytical expression for the volume of deformation of the material as a function of material properties and the impact and critical Stokes numbers.

A Novel Design of Landing Gear Oleo Strut Damper Using MR Fluid for Aircraft and UAV’s

2012 ◽  
Vol 225 ◽  
pp. 275-280
Author(s):  
Chandra B. Asthana ◽  
Rama B. Bhat
Keyword(s):  
Shock Absorber ◽  
Fluid Viscosity ◽  
Simulation Approach ◽  
Body Frame ◽  
Mr Fluid ◽  
Orifice Area ◽  
Aerial Vehicle ◽  
Impact Kinetic Energy ◽  
The Impact ◽  
Novel Design

Most landing gears used in aircraft employ very efficient oleo-pneumatic dampers to absorb and dissipate the impact kinetic energy of the aircraft body frame. A single-acting shock absorber is most commonly used in the oleo strut that has a metering pin extending through the orifice, which can vary the orifice area upon compression and extension of the strut. This variation is adjusted by shaping the metering pin so that the strut load is fairly constant under dynamic loading. In this paper, it is proposed to further change the damping coefficient as a function of time in order to achieve a semi-active control of the aircraft vibrations during landing by using Magnetorheological (MR) fluid in the Oleo. With the metering pin designed for a nominal flight condition, further variation in the fluid viscosity would help achieve the optimal performance in off-nominal flight conditions. A simulation approach is employed to show the effect of different profiles for viscosity variation in the MR fluid. The utility of such a damper can be very well exploited to include different criteria such as the landing distance after touchdown. This type of system can be used also in Unmanned Aerial Vehicle (UAV) application where the focus of design may be to accomplish the task without the consideration of passenger comfort.

SIMULATION OF DYNAMIC EVENT OF IMPACT USING EXPLICIT 3D FEM MODEL AND VALIDATION BY EXPERIMENT AND CONTACT MODELS

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
Akshay Mallikarjuna ◽  
Dan Marghitu ◽  
P.K. Raju
Keyword(s):  
Material Properties ◽  
Permanent Deformation ◽  
Oblique Impact ◽  
Coefficient Of Restitution ◽  
Impact Behavior ◽  
3D Fem ◽  
Dynamic Event ◽  
Contact Models ◽  
Explicit Dynamic ◽  
The Impact

— In this study, an optimized method to simulate the dynamic 3D event of the impact of a rod with a flat surface has been presented. Unlike the 2D FEM based contact models, in this study both the bodies undergoing the impact are considered elastic(deformable) and simulation is the dynamic event of the impact, instead of predefined 2D symmetric contact analysis. Prominent contact models and plasticity models to define material properties in ANSYS are reviewed. Experimentation results of normal and oblique impact of the rod for different rods provided the coefficient of restitution. Experimental results of permanent deformation on the base for different impact velocity is derived out of a prominent impact study. The simulation results are in co-relation with experiment and both indentation and flattening models on the coefficient of restitution (COR) and permanent deformation of the base and rod after the impact. Thus, the presented 3D Explicit Dynamic simulation of impact is validated to analyze the impact behavior of the 2 bodies without any predefined assumptions with respect to boundary conditions or material properties.

A Novel Gemini Cationic Viscoelastic Surfactant-Based Fluid for High Temperature Well Stimulation Applications

2021 ◽  
Author(s):  
Dawn Friesen ◽  
Brian Seymour ◽  
Aaron Sanders
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Chain Length ◽  
Surfactant Concentration ◽  
Gemini Surfactant ◽  
Alkyl Chain ◽  
Friction Reduction ◽  
Fluid Viscosity ◽  
Viscoelastic Surfactant ◽  
The Impact

Abstract Viscoelastic surfactant (VES)-based fracturing fluids can reduce the risk of formation damage when compared with conventional polymer-based fracturing systems. However, many VES systems lose viscoelasticity rapidly under high-temperature conditions, leading to high fluid leakoff and problems in proppant placement. A gemini cationic VES-based system offering thermal stability above 250°F and its efficiency in friction reduction is presented in this paper. Rheology measurements were conducted on viscoelastic cationic gemini surfactant fluids as a function of temperature (70 – 300°F) and surfactant concentration. The length of surfactant alkyl chain was varied to investigate the impact of surfactant chain length on VES fluid viscosity at elevated temperatures. The effect of flow rate on friction reduction capability of the surfactant fluid was measured on a friction flow loop. Foam rheology measurements were conducted to evaluate the VES fluid's ability to maintain high temperature viscosity with reduced surfactant concentration. A gemini cationic surfactant was used to prepare a viscoelastic surfactant system that could maintain viscosity over 50 cP at a shear rate of 100 s−1up to at least 250°F. With this system, viscoelastic gel viscosity was maintained without degradation for over 18 hours at 250°F, and the fluid showed rapid shear recovery throughout. Decreasing the average alkyl chain length on the surfactant reduced the maximum working temperature of the resulting viscoelastic gel and showed the critical influence of surfactant structure on the resulting fluid performance. The presence of elongated, worm-like micelles in the fluid provided polymer-like friction reduction even at low surfactant concentrations, with friction reduction of over 70% observed during pumping (relative to fresh water) up to a critical Reynolds number. Energized fluids could also be formulated with the gemini surfactant to give foam fluids suitable for hydraulic fracturing or wellbore cleanouts. The resulting viscoelastic surfactant foams had viscosities over 50 cP up to at least 300°F with both nitrogen and carbon dioxide as the gas phase. The information presented in this paper is important for various field applications where thermal stability of the treatment fluid is essential. This will hopefully expand the use of VES-based systems as an alternative to conventional polymer systems in oilfield applications where a less damaging viscosified fluid system is required.

scholarly journals A Comprehensive Set of Impact Data for Common Aerospace Metals

2017 ◽  
Vol 12 (6) ◽  
Author(s):  
M. R. W. Brake ◽  
P. L. Reu ◽  
D. S. Aragon
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Model Development ◽  
Coefficient Of Restitution ◽  
Image Correlation ◽  
Plastic Behavior ◽  
Data Set ◽  
Force Resolution ◽  
Impact Data ◽  
The Impact

The results of two sets of impact experiments are reported within. To assist with model development using the impact data reported, the materials are mechanically characterized using a series of standard experiments. The first set of impact data comes from a series of coefficient of restitution (COR) experiments, in which a 2 m long pendulum is used to study “in-context” measurements of the coefficient of restitution for eight different materials (6061-T6 aluminum, phosphor bronze alloy 510, Hiperco, nitronic 60A, stainless steel 304, titanium, copper, and annealed copper). The coefficient of restitution is measured via two different techniques: digital image correlation (DIC) and laser Doppler vibrometry (LDV). Due to the strong agreement of the two different methods, only results from the digital image correlation are reported. The coefficient of restitution experiments are in context as the scales of the geometry and impact velocities are representative of common features in the motivating application for this research. Finally, a series of compliance measurements are detailed for the same set of materials. The compliance measurements are conducted using both nano-indentation and micro-indentation machines, providing sub-nm displacement resolution and μN force resolution. Good agreement is seen for load levels spanned by both machines. As the transition from elastic to plastic behavior occurs at contact displacements on the order of 30 nm, this data set provides a unique insight into the transitionary region.

Size and Temperature Dependent Deposition Model of Micro-Sized Sand Particles

2017 ◽  
Author(s):  
Kuahai Yu ◽  
Danesh Tafti
Keyword(s):  
Contact Force ◽  
Adhesion Force ◽  
Stokes Number ◽  
Experimental Result ◽  
Contact Radius ◽  
Recovery Stage ◽  
Line Force ◽  
Plastic Stage ◽  
Sand Particles ◽  
The Impact

Sand ingestion and deposition in gas turbine engine components can lead to several operational hazards. This paper discusses a physics based model for modeling the impact and deposition of sand particles. The collision model divides the impact process into three stages, the elastic stage, the elastic-plastic stage, and full plastic stage. The recovery stage is assumed to be fully elastic. The contact force, contact radius and work of contact force are conformed to the Hertzian theory, using “Young’s modulus similarity” rule to predict the recovery displacement. The adhesion loss in the recovery stage is considered using Dunn’s model, which describes the adhesion force as an idealized line force with the contact radius. The validation case of steel spherical particle impact on a glass surface with the maximum Stokes number of 10000, shows that the adhesion model with elastoplastic impact model describes the experimental result well. When the Stokes number is less than 12, the particle deposits on the surface. Sand properties are characterized by size and temperature dependencies. Model predictions for particle sizes ranging from 0.5 to 50 micron, impact velocities up to 80 m/s, and temperatures above 1300 K are given and discussed. It is shown that both size and temperature have an effect on the deposition characteristics.

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